1. Field of the Invention
The present invention relates generally to coagulators and, more particularly, to a disposable coagulator for the bipolar coagulation of blood vessels and/or tissue.
2. The Prior Art
Coagulators as herein referred to are electro-surgical instruments designed for the coagulation of blood vessels and/or tissue. For the most part, such coagulators are of the wet field type, i.e., there is no requirement to clear bood and/or other fluid from the operating field before using the coagulator; in fact wet field type coagulators work better in a wet field.
Initially, such wet field coagulators were of the mono-polar kind. In a mono-polar coagulator, the current flows from the instrument randomly through the body to a ground plate placed on the patient distant from the operative site. This can, on occasion, produce a ground plate burn. Additionally, the mono-polar coagulator can be responsible for cross-cardiac difficulties.
To overcome these difficulties, bipolar coagulators have been developed. Bipolar coagulators essentially are forceps employing a two-point coagulation technique with two forceps blades insulated from one another. The coagulating current passes from one forceps tip to the other, so only the vessel and/or tissue held between the tips is coagulated. This pinpoint coagulation results in less surrounding tissue being damaged, and the need for a ground plate is eliminated. Bipolar coagulation has been found particularly advantageous in ophthalmic surgery, ear-nose-throat (ENT) surgery, plastic surgery, neurosurgery, orthopaedic surgery, cardiovasuclar surgery and thoracic surgery, where in each instance precise hemostasis is critical. See S. D. McPherson, Jr., M.D. "Bipolar Coagulation in Ophthalmic Operations," Am. J. of Ophthalmology, 73:5, 1972; K. Reed, M. D. and C. J. Snider, M.D. "Bipolar Forceps for Electrocautery in Tonsillectromy," Transactions, Vol. 78, July-Aug., 1974, No. 4; S. Charles, M.D., J. White, C. Dennison and D. Eichenbaum, M. D. "Bimanual, Bipolar Intraocular Diathermy," Am. J. of Ophthalmology, 81:1, 1976; and M. A. Kass, M.D., S. D. Hersh, M.D. and D. M. Albert, M.D. "Experimental Iridectomy with Bipolar Microcautery," Am. J. of Ophalmology, 81:4, 1976.
Bipolar coagulation, as heretofore practiced, does have its share of drawbacks, however. For one, it is dependent on the user's skill, dexterity and absence of fatigue in manually positioning, with just the correct force and separation, the two forceps blades about the vessel or tissue to be coagulated and for holding it there during the time period that the coagulating current is passed therebetween. In addition to effecting and maintaining exacting control of the area to be coagulated, which is no easy task in view of the smallness of such an area, usually measured in millimeters or fractions thereof, the user has to repeat the coagulation process several times, perhaps many times until all areas in the operative site have been coagulated. The user, at best, can only approximate the sameness in the force and separation of the two forceps blades as he goes on coagulating one affected area after another. Yet, the distances separating the tips of the forceps have a direct bearing on the power requirements for the instrument. For, with a wider separation between the tips of the forceps, more power will be required to effect a good coagulation than with a narrower separation.
While power settings of the coagulator can be changed in between coagulations, the power settings cannot be changed during the time period that the coagulation current is passed between the forceps tips. Further, for the user to keep changing the power settings even in between coagulations is, at best, an unwelcome distraction from the task at hand. For the most part, surgeons like to stick with the power settings they set for most, if not all, the coagulation they do at a given operative site. Consequently, since there is bound to be variations, however slight, between successive coagulation spacings separating the foreceps tips, the resultant tissue coagulation will vary in terms of unwanted tissue damage to the surrounding tissue. Thus, the lesion produced from one coagulation to the next will be different.
Furthermore, tissue to metal adhesion at the tips of the forceps is at times a problem, stemming in part from the difficulty in smoothly polishing the forceps tips, particularly if they have a hard carbide surface. Also, when pressing a vessel or tissue together, the surgeon may unwittingly short out the coagulating current between the tips by in fact forcing portions of the conducting forceps blades into contact with each other. Still further, the coagulator forceps are expensive to make and must be sterilized after each operative use.